Furnace



Jan. 13, 1925.

W. M. DUHNCAN FURNACE iled Nov. 19, 1920 3 Sheets-Sheet l s smeets-she` 2 Jan, 13, 1925.

w. M. DUNCAN FuRNAcE Filed Nov. 19. 1920 Jan. 13, 1925- 1,522,812

W. M. DUNCAN FURNACE Filed Nov. 19, 1920 3 SheetsSheet 5 ENQ Patented dan. i3, i925,

WILLIAM M, DUNCAN, OF ALTON, ILLINOIS.

FURNACE.

Application filed November 19, 1920. Serial No, 425,242.

T 0 all whom t 'may @0n-cern:

Be it known that I, WILLIAM lvl. DUNCAN, a citizen of the United States of America, a resident of Alton, in the county of Madison, State of Illinois, have invented certain new and useful Improvements in Furnaces, of which the following is a full, clear, and exact description, reference being had to the accompanying drawings, forming part of this specification.

This invention relates to improvements in furnaces, and the novel features of the invention are adapted for use in a furnace provided with a traveling chain grate. One of the objects of the invention is to produce a novel draft device providing for a comparatively uniform combustion of the fuel at the middle and marginal portions of the grate. Another object is to prevent leakage of draft and fuel between the side edges of a chain grate and the side frames which support the grate.

Prior to this invention, furnace grates have been located between furnace walls which become very hot, and as a result of the intense heat radiated from these walls, extremely7 high temperatures are maintained in the fuel near these walls, so the fuel at the side margins of the grate is ordinarily consumed more rapidly than the fuel at the middle portion of the grate. r1fhis is undesirable in a furnace ofany kind, and especially in a forced draft furnace provided with a traveling chain grate. If the fuel is quickly consumed and rapidly converted into ashes at the side margins of the grate, the draft will freely pass through these margins, thereby reducing the efficiency of the apparatus by dissipating the draft which escapes through the side margins, and at the same time reducing the force of the draft at the middle portion of thergrate where draft is needed for proper combustion. Therefore, it is undesirable to transmit a uniform draft to the middle and side margins of the fuel bed, for vthe fuel at the'side margins is subjected to the intense heat radiated from the side walls of the furnace, and if these margins are also subjected to a severe draft, the marginal portions of the fuel will be consumed very rapidly, with the result of wasting the draft which should be used to promote combustion between these side margins.

The present invention comprises-a draft device whereby the middle portion of the grate is supplied with the necessary draft, while the draft is excluded or reduced at the side margins of the grate. As a result of this non-uniform delivery of draft, the fuel will not be so rapidly consumed at the side margins where it is subjected to the heat of the furnace walls, and the draft intended for combustion between these margins cannot freely escape through said margms.

More specifically stated, the apparatus about to be described includes marginal draft shields located below the side margins of the grate where they Serve as baffles or obstructions tending to prevent free delivery of draft to said side margins, and these draft shields are preferably adjustable to vary the draft exposed area between the side margins of the grate.

With the foregoing and other objects in view, the invention comprises the novel construction, combination and arrangement of parts hereinafter more specifically described and illustrated in the accompanying drawings, wherein is shown the preferred embodiment of the invention. However, it is to be understood that the invention comprehends changes, variations and modifications which co-me within the scope of the claims hereunto appended.

Fig. I is a longitudinal section, illustrating a mechanical Stoker embodying the features of this invention, the middle portion of the apparatus being broken away.

Fig. II is a transverse section of the structure shown in Fig. I.

FiO. III is a diagrammatical top view showing the draft boxes and the marginal draft shields at the ends of these boxes.'

To illustrate the invention, I have shown a mechanical stoker comprising an endless chain grate A supported between side frame members l mounted on wheels 2, The chain grate comprises many grate links 3 connected by means of pivot rods 4 arranged trans-- versely of the grate. A power shaft 5 (FigA I), supported by the side frames i, is provided with any desired number of sprocket wheels 6 for transmitting movement to the endless chain grate. The chain grate passes around the sprocket wheels 6 and also around a plain idle wheel, or roller 7, the latter' being mounted on a shaft 8. The fuel passes from a hopper 9 to the top face of the grate, as indicated by arrows in Fio'. I.

The furnace is provided with suitable side walls B, including refractory members 10 located adjacent to the side margins of the `grate. The lower portion of one of these side walls B is hollow, as shown in Fig. ll, to provide an inlet passageway 11 for the draft. 12 designates draft boxes surrounded by the traveling grate and extending from a side frame 1 at one side of the grate to the frame 1 at the otherl side. All of these boxes are open at the top to providefor the delivery of the draft to the grate. Nipples 13 may be used to connect the respective draft boxes 12 to the draft passageway 11. Each draft box 12 may also be provided with a nipple 14 (Fig. Il) for the discharge of ashes into a. tubular member 15 provided with a normally closed door' 16.

The several draft boxes 12 are located ad# jacent to each other, and they may be separated by friction members 17 (Fig. l) vover which the grate links travel. 18 designates supporting bars located over the draft boxes 12 to forni supports for the upper portion of the grate, and 19 designates similar bars loca-ted below and engaged by the lower portion of the traveling` grate.

As a means for preventing fi'ee delivery of draft to the fuel at the side marginsof the grate, I have shown two rows of shields 20 adapted to extend through the side walls of the furnace and also through the side frames 1, so as to lie partly within the ends of the draft boxes 12. Guides 21, located in the end portions of the draft boxes, are adapted to receive the side edges of the shieldsy 20. Each shield 20 is provided with Van operating handle 22 located at the exterior of the furnace, and it will be readily understood that the several shields 20 may be adjusted independently of each other.

Each shield 2O lies below and adjacent to a side margin of the grate. aiidit can be adjusted to the position illustrated at the left side of Fig. H wherein it does not interfere with the admission of draft to the grate. or it may occupy Ythe position illustrated at the right side of Fig. Il wherein it will prevent free delivery of draft to the relatively wide marginal portion of the grate. In all of its positions, the -sliield'is parallel with the fuel supporting portion of the grate, and it can be adjusted. in straight lines toward and away from the middle portion of the grate. Vhen the apparatus is in operation, the draft shields 2() will ordinarily be adjusted to intermediate positions shown by the di'agi'ainmatical view (Fig.

III). .ln this view the area of the top sur-V face ofthe grate is indicated by dot and dash lines, andy it will be understood that 4the shields 2O prevent free delivery of draft to the'side margins of thefuel resting onthe top ofthe grate.

When the apparatus is in service, the side margins of the bodyT of fu'el willbe subparatively uniform. and the forced draftY deliveied to the draft boxes will not bepermitted to escape freely at the margins. This draft will be effectively utilized to promote` combustion between the margins of the fuel bed.

Another feature of the invention lies iii a means for closingthe spaces between the side frames 1 and the traveling grate. Closui'e bais 23 are mounted on the side frames 1 as shown by Figs. H andA Hl, and each of said closure bars is slotted to receive'bolts 24 whereby the bars are adjustably secured to the side frames. The grate links 3 (Fig. Il) at the sides of the traveling grate are provided with flanges which extend'over and engage the closure bars 23, and said closure bai-s are adjustab-le transversely of said flanges.

The side frames 1 are usually very large, inaccurate castings, and the grate links are usually made of inaccurate castings. lit is therefore customary to leave spaces between the side frames and the grate. The closure bars 23 can be accurately adjusted to close these spaces, thereby preventing loose particles offuel from dropping between the sido frames and the grate links at the sides of the chain grate. l'V preferably use a series of bars 23 at each side ofthe grate, as shown by Fig. Ill. and the several bars in each seriesA may be adjusted independently of each other.

I claim: Y

1. A furnace provided with heat-radiating side Walls, an endless traveling fuel-sup porting grate, the side margins of the fuelsupporting` portion of said grate being located adjacent t-o said heatradiating side'V walls, and draft shields arranged belowv and(V adj acent to the side margins of the fuel-supporting` portion of said grate so as .to ob'- struct the passage of draft through the niarginal portions of said fuel-supporting portion of said grate Without obstructing the passage of draft between said marginal portions, said shields being approximately co` extensive with the side margins of the fuelsupporting portion of the grate and adjustable in straight lines toward and away 'from the middle of said fuel-supporting portion to vary the draft area at the sides of.` the grate Without aect-ing the drafty between said side margins. j

Y 2. A furnace provided with heatfradiating side Walls, an endless traveling fuel-'supporting grate, the side margins of theups" f;

per portion of said grate being located adjacent to said heat-radiating side walls, draft boxes arranged transversely of and surrounded by said endless traveling grate, said draft boxes being open at the top to provide for the delivery of draft through the upper portion of said endless grate, and marginal obstructions located near the end portions of said draft boxes to prevent free delivery of draft to said side margins of the grate, said marginal obstructions being parallel with the fuel supporting portion of the grate and adjustable in straight lines toward and away from the middle portion of the grate to vary the width of the draft exposed middle portion of the grate.

3. A furnace provided with heat-radiating side walls, an endless traveling fuel-supporting grate, the side margins of the upper p0rtion of said grate being located adjacent to said heat-radiating side walls, draft boxes arranged transversely of and surrounded by said endless traveling grate, said draft boxes being open at the top to provide for the delivery of draft through the upper portion of said endless grate, marginal draft shields slidably mounted in the end portions of said draft boxes at points below and adjacent to said side margins of the grate, and means for sliding said marginal draft shields toward and away from the middle portion of the grate.

4. A furnace provided with heat-radiating side walls, an endless traveling fuel-supporting grate, the side margins of the upper portion of said grate being located adjacent to said heat-radiating side walls, draft boxes arranged transversely of and surrounded by said endless traveling grate, said draft boxes being open at the top to provide for the delivery of draft through the upper portion of said endless grate, marginal draft shields mounted in the end portions of said draft boxes at points below and adjacent to said side margins of the grate, guides permitting said draft shields to move in straight lines parallel with the fuel-supporting portion of the grate, and means for adjusting said marginal draft shields in said straight lines toward and away from the middle portion of the grate, said adjusting means including operating members at the exterior of the furnace.

5. A furnace provided With heatfradiating side walls7 an endless traveling fuel-supporting grate, the side margins of the upper portion of said grate being located adjacent to said heat-radiatino` side walls, draft boxes arranged transversely of and surrounded by said endless traveling grate, said draft boxes being open at the top to provide for the delivery of draft through the upper portion of said endless grate, marginal draft shields mounted in the end portions of said draft boxes at points below and adjacent to said side margins of the grate, and means for adjusting said marginal draft shields in straight lines toward and away from the middle portion of the grate, said adjusting means including independently adjustable operating members permitting said draft shields to be adjusted independently of each other.

6. A mechanical stoker comprising side frame members, a chain grate operable between said side frame members, and a closure bar adjust-ably mounted on one of said side frame members, the grate links at one side of said chain grate being extended over the inner edge of said adjustable closure bar.

T A mechanical Stoker' comprising side frame members, a chain grate operable between said side frame members, closure bars mounted on and extending inwardly from said side frame members, the grate links at the sides of said chain gratel being provided with flanges which extend over and engage said closure bars, and said closure bars being adjustable transversely of said flanges.

ln testimony that I claim-the foregoing I hereunto affix my signature.

DAVID A. BOSVELL. 

